Portable power driven hammer



Patented Aug. 18, 1942 unirao PQRTAELE POWER DRIVEN HAMIMER Harold F. Mossberg, New Haven, Conn, assignor to 0. F. Mossberg & Sons, 1110., New Haven, Conn, a corporation of Connecticut Application February 24), 1940, Serial No. 319,854-

8 Claims.

This invention relates to power driven hammers and more particularly to a power driven hammer of the portable type having a power driven rotating member and means to convert the rotary movement thereof into a reciprocating movement to actuate a reciprocable tool.

One object of this invention is to provide an improved form of portable power driven hammer.

Another object of this invention is to provide an improved portable hammer of the above nature wherein the shock occasioned by the blow of a reciprocable member upon a tool will not be transmitted to the driving member and its force may be varied by the operator.

Still another object is to provide an improved hammer mechanism having means to readily attach it to, and to detach it from, a standard form of rotary electric drill, or the like.

Further objects are to provide an improved portable power driven hammer of the above nature with; improved means to hold a reciprocable tool in operative position thereto; improved means to convert rotary movement into reciprooable movement; and means to shield the operator from flying chips, and like scrap, formed during the operation thereof.

A further object of this invention is to provide an improved portable power driven hammer which will be relatively inexpensive to manufacture, simple in construction, and which is very efficient and durable in use.

With these and other objects in view, which Will appear as the description proceeds, there has been illustrated in the accompanying drawing, one form in which the features and principles of this invention may be conveniently embodied in practice.

In the drawing, wherein like reference numerals designate like parts throughout the several views:

Figure 1 is a side elevational view of a portable power driven hammer embodying the features and principles of this invention;

Figure 2 is an enlarged broken longitudinal sectional view of the principal operable parts of this invention in one position;

Figure 3 is a cross-sectional View taken on the line 3-3 of Figure 2;

Figure 4 is a cross-sectional view taken on the line 44 of Figure 2;

Figure 5 is a cross-sectional view taken on the line 55 of Figure 2;

Figure 6 is a cross-sectional view taken on the line 6-5 of Figure 2;

Figure 7 is a, broken longitudinal sectional view 55 similar to Figure 2 but showing the operable parts thereof in another position in the operation of the device; and

Figure 8 is a detail side view of a part of the device.

Herein the improved portable power driven hammer of this invention is shown arranged to be driven from a rotatable shaft ll, extending outwardly from one end of a casing l2 which houses an electrical motor (not shown) adapted to be energized by being connected to a source of electric power by means of an electrical cable [3 which, in this instance, extends into a handle l4 provided on the casing I2 and thence to the motor.

The shaft H and casing l2, in this instance, are parts of a standard form of electrical drill and therefore the shaft H has a drill, or like, shank holding chuck mounted upon its outer end. In this instance, the motor casing I2 has an extension 5 in which is housed suitable reduction gearing (not shown). The housing extension 16 has a bearing boss I! in which the shaft II is journaled, and, in this instance, the boss 11 is provided with exterior screw-threads l8, whereby a sleeve I9, having interior screw-thread therein corresponding with the threads [8, may be screw-threaded thereon. In addition to the threads [8, or in place thereof, the sleeve [9 may be detachably secured on the boss I! by a set screw [0. The chuck I5 is of the usual type having a rotatable sleeve 20 adapted to close the usual jaws in a cylindrical member 2| and actuated by means of the usual Wrench (not shown) but which is located in holes 22 in the member 2! and engages gear teeth 23 on the sleeve 20 to rotate the latter and open and close the jaws of the chuck I5.

The above described structure may constitute the power driving means for this invention, but it is to be understood that, in some instances, the motor and gearing in the casings l2 and I6 respectively may be omitted and other means, such as a flexible shaft from a remotely disposed power source (not shown), may be provided to power drive the shaft ll upon which the chuck it is mounted. In such cases the power driven shaft II will be journaled in a boss, or member, similar to a combined structure of the boss ll and the sleeve IS. The means, cooperating with the power driven shaft ll through the chuck l5, to convert the rotary movement of the shaft ll into reciprocating movement, whereby a tool, such as a chisel 24, may be reciprocated, includes a hollow open-ended cylindrical casing 25 having a hollow cylindrical stem 26 extending from the closed end thereof and in which the tool 25 may be detachably mounted. A collar, or band, 21 encircles the hollow stem 25 substantially midway of its length to support a coneshaped sheet metal shield 28.

The shield 23, in this instance, is provided with a cylindrical hub portion 29 adapted to snugly fit over the stem 2b and seat against the collar 2'5, and has an outwardly and upwardly curved flange, or rim 3i extending about its peripheral edge adapted to catch and hold chips and the like. A window 533 of suitable transparent material is provided in the shield 23 through which an operator may observe the tool 2 1" and the article being worked upon. Obviously, the entire shield 28 could be made of transparent material. T116 object of providing a shield 2'8, is to protect the operators eyes, face, and head, from flying chips cut from the work, especially if it is disposed overhead, by the tool 2%. The shield 28 being readily removed from the stem 26, need not be used when the work is so disposed that the tool' Ed is held horizontally", or pointed downwardly.

The hollow casing 25' is open at its end 3'2 '1)- posite to the stem '26 and is bored out to fit snugly over the sleeve [9. An air inlet is provided in the stem end of the casing 25 and a plurality of openings ii) are formed in its side wall for ventilation and to facilitate oiling. A number of axially directed slots 33, in this instance four, are provided in the casing? end 32, and a peripherally directed slot 35 extends from the inner end of each slot 33. Lugs 35, herein four, extend outwardly from the periphery of the sleeve: t9 and are adapted to enter the slots 33, when'the casing 32 is slipped over the sleeve 89, and then to enter the slots 35, when the casing 25 is rotated upon the sleeve E8, to lock the casing.- 25

to the sleeve 1%. A le'at spring 35, fastenedat one end to the casing 25 by ascrew 3 extends toward the casing end 32- and, by having its end 33 curved downwardly, is adapted to snap into one ofthe slots- 33 in back of the lug 35 and in the communicating slot prevent the accidental rotation of the casing 25 with respect to the sleeve is whereby these parts might-become disconnected.

A cylindrical plunger, or hammer adapted to freely slide and rotate in the bore M of the casing- 2-5', has a hammer portion 22, of smaller diameter than the plunger 33, extending fromone of its ends, or itsfront end, into a bore 63 of the stem 23-. The plunger 39 has a-portion M which is reduced in diameter adjacent the extending hammer portion 32 to form ashoulder 45 facing the portion 42. The shoulder 55 is' formed to provide, in this instance two; camming surfacesdfi and 4 3', which are adapted to engage a pin i' rotatably mounted in the casing 25, when the plunger is rotated, to force it' backwardly toward the chuck Hi; as shown in- Figure 7. The pin id is journaled in aboss 49, provided on the casing 25, and extends through the same and has an annular grooveiit in its outer end, wherein a spring washer 52' is seated to retain the pin 58 in the boss 28: A- shoulder 53 formed on the end of the plunger portion id, between it and the hammer portion 62, is adapt ed to normally engage and seat on the bottom surface 54 of the bore li in the casing 25" when the plunger ssis in its forward position and at rest, as shown in Figure 1. When the plunger 39 is in such position the camrning shoulder iii,

or 31, as the case may be, is out of engagement with the pin 48.

The plunger 39 is counterbored out at its end opposite the hammer portion 42, or rear end 5 5, to receive a relatively strong coiled compression spring 56 which is adapted to react between the bottom 57 of the counterbore portion 58 and a flat disc-like end 53 of a driving member 65. The driving member 6! has a shank 62 extending rearwardly from the disc-like end 59 to be received and tightly clamped in the jaws of the chuck it. The member ti also has oppositely directed tongues 63 and 6 extending radially therefrom, which are adapted to enter, and to slide axially in, corresponding slots 65 and 6'6 provided in the plunger 39 and extending inwardly from the rear end thereof. The tongues :33 and (i=3 extend outwardly to closely adjacent the periphery of the plunger 39 and have their rear surfaces 67 and G8 engaged by a split single coil spring 69 seated in an annular groove it formed in the periphery of the plunger 39' adjacent its rear end 55. The spring 69 consti tutes the' means to hold the driving member 6|, spring 55, and the plunger 39 together for assembly, as a unit, to' thechuck to:

The tool 2 2 is provided with a shank TZadapted to enter a bore portion 13 in the stem 25 and have its inner end I l abruptly engaged by the outer end 75 of the hammer'portion 12 under the" urge of the spring 56, when the pinrotates'offof the high point 60 of either of the camming shoulders it or ll, and thereby produce asharp' blow upon the work at the cutting edge it of the" tool 24. The tool shank 12 is provided with an axially elongated annular groove T 1 i'nwhich-a pin' T8, slidably mounted inthe stem 26, is adapted to-lie' to catch and retain the tool 24 in the stem 26. The pin 18 is constantly urged inwardly'byasplit flat ring-shaped spring 79, whichpartially encircles the stem 2'6 and overlies the outer end of the pin 18.

The tool inner end i4 is normally maintained out of contact with the hammer portionend 15', see Figure l, by aspring pressed pin 81 which engages a rearwardly facing shoulder 82 formed between the shank l2 and the body 83'-of the-tool, which body 83 is made somewhat-larger in diameter than the toolshank 12' for this purpose. The arrangement is such that the pin 1 8 engages the rear shoulder 84 of the annular groove 11 and prevents the tool shank '12 from d'roppin'g'out of the stem 2%. The pin 18- also limits theamodnt the shank end Mr is spaced out of contact with the hammer portion end 15. The length of the tool shank 72 is such that the shoulder 82 is spaced from the outer end of the sten'r 26 a greater amount than the amount the ends 14 and '55 are spaced apart, so that the latteren'dsmay be engaged in varying degree when the tool end It is pressed against the work and the piunger 39 is rotated, while the shoulder 82 and stem end will not engage.

From the above it is obvious that a portable power driven hammer has-'beenprovided' which may be readily and securely connected to any power driven shaft I I, such as one j'ourna'ledinj a sleeve l9 and having a chuck i'ds'ecured' thereto,

for efiicient operation thereby, the shaft being.

one either extending from a motor, or' otherwise. This advantage is obtained by' the simple expedients of clamping the shank B2 of the driving member 6| into the chuck ii} on the" shaft ;H

and then slipping the casing 2'51 overth'e plunger 39, assembled to the member 51', and locking the casing to the sleeve by the cooperating slots 33, 34 and lugs 35.

After connecting and assembling the device to the power driven shaft II and its supporting sleeve I9, power may be applied to drive the shaft II, whereupon the plunger 39 will be rotated in the casing 25. Rotation of the plunger 39 will cause it, in this instance twice every revolution, to alternately slide rearwardly, by the cooperating action of the pin 48 and the camming shoulders 46 and 41, and abruptly forwardly, under urge of the spring 56, to impose hammer-like blows upon the tool end 14, and through the tool 26 to upon the work against which the tool has been pressed.

Due to the provision of the rotatable pin 48 which rides with minimum friction upon the camming shoulders 46 and 41', a minimum of power is required to drive the plunger 39. Likewise the wear at this point, due to friction, is negligible and easily compensated for by the simple expedient of replacing the pin 48 with a new and relatively inexpensive one.

Due to the cooperating arrangement of the plunger 39 and the driving member 6|, as above described, no appreciable shock is transmitted to the shaft I I, which, should this shaft be the shaft of a motor or the like, might cause serious damage. When in operation, the reciprocating motion given the hammer portion 42 is directly and wholly transmitted to the tool 24, as the shoulder 53 is held against contact with the bottom 54 of the bore 4| due to the pressure exerted against the tool 24. Thus no appreciable power is absorbed and lost, nor is any shock sustained by the casing 25, or the shaft II, as pressure upon the tool end 15 to press it against the work is obtained from the handle I4, through the casing I2 and I6, the chuck I5, the driving member 6|, the spring 55, the plunger 39, the hammer portion 25. Passing as it does through the spring 56 any reacting shock imposed upon the plunger 39 will be considerably cushioned by this spring before it can be appreciably transmitted back to the casing I2, and thus no appreciable power is absorbed by the casing I2 and lost. Due to this floating arrangement of the plunger 39 when the tool 26 is pressed against the work the force of the blow given to the work may be varied under control of the operator, the more pressure applied causing a heavier blow, and the lesser pressure a lighter blow, Such an arrangement is particularly advantageous when the tool is used for carving, or any other work requiring a variation in the force of the blow.

While there has been shown and described herein, one form of an improved portable power driven hammer, it is to be understood that the invention may be embodied in other forms without departing from the spirit and essential attributes thereof. It is therefore desired that the present embodiment be considered in all respects as illustrative, and not restrictive, and it will be further understood that each and every novel feature and combination thereof, present in, or possessed by, the device herein disclosed, forms a part of the invention included in this specification.

What is claimed as new and for which it is desired to secure Letters Patent is:

1. In a portable power driven hammer, a casing having a bore, a plunger slidably mounted in the bore of said casing, said plunger having a camming shoulder at one end and a counterbore in its other end, means carried by said casing to ber in the bore in said plunger and being slidable axially therein, a spring in the bore in said plunger between said driving member and said plunger, said plunger having an axially directed slot through a side wall thereof and communicating with the bore therein, said driving mem ber having a tongue thereon extending radially therefrom into the slot in said plunger to drivingly connect them, and means to drivingly connect said driving member to a power driven shaft.

2. In a portable power driven hammer, a casing having a bore, a plunger slidably mounted in the bore of said casing, said plunger having a camming shoulder at one end and a counterbore in its other end, means carried by said casing to ride on said camming shoulder, a driving member in the bore in said plunger and being slidable axially therein, a spring in the bore in said plunger between said driving member and said plunger, said plunger having an axially directed slot through a side wall thereof and communicating with the bore therein, said driving member having a tongue thereon extending radially therefrom into the slot in said plunger to drivingly connect them, an annular groove about the counterbored end of said plunger, and a spring in a the said annular groove extending across the slot ride on said camming shoulder, a driving memin said plunger to retain said driving member tongue therein, said driving member having a shank for connection with a source of rotative motion.

3. In a portable power driven hammer, a casing having a bore, a plunger slidably and rotatably mounted in the bore of said casing, said plunger having a tool striking portion at one end and a counterbore in its other end, and a slot extending transversely across the counterbored end, a driven member having a tongue axially slidably in the slot in said plunger, means on said plunger to retain said tongue in the slot in said plunger, and spring means reacting between said plunger and said driven member to urge said tongue toward said retaining means.

4. In a portable power driven hammer, a tool engageable hammer unit comprising a plunger having a camming surface at one end and a counterbore in its other end, a part slidable in the counterbore in, and drivingly connected to, said plunger, said part having a portion extending from said plunger and connectable to a rotatable shaft, a spring in the counterbore in said plunger to react between said part and said plunger, and releasable means carried by said plunger and adapted to be engaged by said part to normally retain said part against movement from said plunger by said spring.

5. In a portable power driven hammer, a tool engageable hammer unit comprising a plunger having a camming surface at one end and a counterbore in its other end, a part slidable in the counterbore in, and drivingly connected to, said plunger, said part having a portion extending from said plunger and connectable to a rotatable shaft, a spring in the counterbore in said plunger to react between said part and said plunger, releasable means carried by said plunger and adapted to be engaged by said part to normally retain said part against movement from said plunger by said spring, and a one-piece casing adapted to be releasably connected to a shaft support and having a bore open at one end thereof, said casing carrying a rotatable pin and being adapted to freely slide over said hammer unit to disposed said pin in operative cooperation with said camming surface and to slidably support said plunger upon the surface of its bore.

6. Ina portable power driven: hammer, a hammer unit comprising a plunger having a tool engaging end and a count'erbore in its opposite lend a spring in the counterbore in said plunger, a

drical plunger having atool engaging end and a. counterbore in its opposite end, a spring in the.

counterbore in said plunger, a part slidable in the counterbore in said plunger and having an abutment engaged by said spring, means on said part to drivingly connect said part to saidplunger,

and a spindle on said part adapted to beacon-- nected to a driven shaft and extending out" of the count'erbored end of saidplunger, saidplunger having a portion ofreduceddiameter between its ends and a camming surface extending beyond theperipher-y of said portion, said casing adapted tobe releasably; connected to'a'shaft support and having a boreopen at one end thereof, said casing carrying a rotatable pin and being adapted to freelyslideover said hammer unit to dispose said pin atthe reducedportionof the plunger. in operative cooperation with said camming surface, and to slidably support said plunger Within and upon the surface of its bore.

8. In a power driven hammer, a, casing having a bore, a hammer plunger reciprocable in. the bore in said casing, an extension on one end of said casing and having a, bore, a tool shank slidable in: the bore insaid extension, a pin extendingthrough said extension into an elogated slot in said tool shank, and a split spring band encircling said extension to resiliently hold saidpin in place.

HAROLD F. MOSSBERG. 

